From 6cca3981113fdd1d9796fab0f8d8fd7d9b3d13d3 Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Fri, 20 May 2022 16:40:58 +0100
Subject: [PATCH 1/8] Port SemigroupK and MonoidK to new derivation scheme

---
 .../scala-3/cats/derived/DerivedMonoidK.scala | 27 +++++++++++++++++++
 .../cats/derived/DerivedSemigroupK.scala      | 24 +++++++++++++++++
 .../main/scala-3/cats/derived/monoidk.scala   | 12 ---------
 .../main/scala-3/cats/derived/package.scala   | 12 ++++-----
 .../scala-3/cats/derived/semigroupk.scala     | 14 ----------
 .../scala-3/cats/derived/MonoidKTests.scala   |  2 +-
 .../cats/derived/SemigroupKTests.scala        |  3 +--
 7 files changed, 58 insertions(+), 36 deletions(-)
 create mode 100644 core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
 create mode 100644 core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
 delete mode 100644 core/src/main/scala-3/cats/derived/monoidk.scala
 delete mode 100644 core/src/main/scala-3/cats/derived/semigroupk.scala

diff --git a/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
new file mode 100644
index 00000000..9b8925f6
--- /dev/null
+++ b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
@@ -0,0 +1,27 @@
+package cats.derived
+
+import cats.{Monoid, MonoidK}
+import shapeless3.deriving.{Const, K1}
+
+import scala.compiletime.*
+
+type DerivedMonoidK[F[_]] = Derived[MonoidK[F]]
+object DerivedMonoidK:
+  type Or[F[_]] = Derived.Or[MonoidK[F]]
+  inline def apply[F[_]]: MonoidK[F] =
+    import DerivedMonoidK.given
+    summonInline[DerivedMonoidK[F]].instance
+
+  given [T](using T: Monoid[T]): DerivedMonoidK[Const[T]] = new MonoidK[Const[T]]:
+    final override def empty[A]: Const[T][A] = T.empty
+
+    final override def combineK[A](x: Const[T][A], y: Const[T][A]) = T.combine(x, y)
+
+  given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedMonoidK[F] =
+    given K1.ProductInstances[MonoidK, F] = inst.unify
+    new Product[MonoidK, F] {}
+
+  trait Product[T[x[_]] <: MonoidK[x], F[_]](using inst: K1.ProductInstances[T, F])
+      extends MonoidK[F],
+        DerivedSemigroupK.Product[T, F]:
+    final override def empty[A]: F[A] = inst.construct([t[_]] => (emp: T[t]) => emp.empty[A])
diff --git a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
new file mode 100644
index 00000000..c6b92342
--- /dev/null
+++ b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
@@ -0,0 +1,24 @@
+package cats.derived
+
+import cats.{Semigroup, SemigroupK}
+import shapeless3.deriving.{Const, K1}
+
+import scala.compiletime.*
+
+type DerivedSemigroupK[F[_]] = Derived[SemigroupK[F]]
+object DerivedSemigroupK:
+  type Or[F[_]] = Derived.Or[SemigroupK[F]]
+  inline def apply[F[_]]: SemigroupK[F] =
+    import DerivedSemigroupK.given
+    summonInline[DerivedSemigroupK[F]].instance
+
+  given [T](using T: Semigroup[T]): DerivedSemigroupK[Const[T]] = new SemigroupK[Const[T]]:
+    final override def combineK[A](x: Const[T][A], y: Const[T][A]) = T.combine(x, y)
+
+  given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedSemigroupK[F] =
+    given K1.ProductInstances[SemigroupK, F] = inst.unify
+    new Product[SemigroupK, F] {}
+
+  trait Product[T[x[_]] <: SemigroupK[x], F[_]](using inst: K1.ProductInstances[T, F]) extends SemigroupK[F]:
+    final override def combineK[A](x: F[A], y: F[A]): F[A] =
+      inst.map2[A, A, A](x, y)([t[_]] => (smgrpk: T[t], x: t[A], y: t[A]) => smgrpk.combineK(x, y))
diff --git a/core/src/main/scala-3/cats/derived/monoidk.scala b/core/src/main/scala-3/cats/derived/monoidk.scala
deleted file mode 100644
index cc5e878c..00000000
--- a/core/src/main/scala-3/cats/derived/monoidk.scala
+++ /dev/null
@@ -1,12 +0,0 @@
-package cats.derived
-
-import cats.{Monoid, MonoidK}
-import shapeless3.deriving.{Const, K1}
-
-trait ProductMonoidK[T[x[_]] <: MonoidK[x], F[_]](using inst: K1.ProductInstances[T, F])
-    extends ProductSemigroupK[T, F],
-      MonoidK[F]:
-  def empty[A]: F[A] = inst.construct([t[_]] => (emp: T[t]) => emp.empty[A])
-
-trait MonoidKDerivation:
-  extension (F: MonoidK.type) inline def derived[F[_]](using gen: K1.Generic[F]): MonoidK[F] = ???
diff --git a/core/src/main/scala-3/cats/derived/package.scala b/core/src/main/scala-3/cats/derived/package.scala
index a3add49d..debf0a67 100644
--- a/core/src/main/scala-3/cats/derived/package.scala
+++ b/core/src/main/scala-3/cats/derived/package.scala
@@ -24,14 +24,10 @@ extension (x: Functor.type) inline def derived[F[_]]: Functor[F] = DerivedFuncto
 extension (x: Reducible.type) inline def derived[F[_]]: Reducible[F] = DerivedReducible[F]
 extension (x: Traverse.type) inline def derived[F[_]]: Traverse[F] = DerivedTraverse[F]
 extension (x: NonEmptyTraverse.type) inline def derived[F[_]]: NonEmptyTraverse[F] = DerivedNonEmptyTraverse[F]
+extension (x: SemigroupK.type) inline def derived[F[_]]: SemigroupK[F] = DerivedSemigroupK[F]
+extension (x: MonoidK.type) inline def derived[F[_]]: MonoidK[F] = DerivedMonoidK[F]
 
-object semiauto
-    extends ContravariantDerivation,
-      InvariantDerivation,
-      MonoidKDerivation,
-      PartialOrderDerivation,
-      SemigroupKDerivation,
-      Instances:
+object semiauto extends ContravariantDerivation, InvariantDerivation, PartialOrderDerivation, Instances:
 
   inline def eq[A]: Eq[A] = DerivedEq[A]
   inline def hash[A]: Hash[A] = DerivedHash[A]
@@ -51,6 +47,8 @@ object semiauto
   inline def traverse[F[_]]: Traverse[F] = DerivedTraverse[F]
   inline def nonEmptyTraverse[F[_]]: NonEmptyTraverse[F] = DerivedNonEmptyTraverse[F]
   inline def show[A]: Show[A] = DerivedShow[A]
+  inline def semigroupK[F[_]]: SemigroupK[F] = DerivedSemigroupK[F]
+  inline def monoidK[F[_]]: MonoidK[F] = DerivedMonoidK[F]
 
 object auto:
   object eq:
diff --git a/core/src/main/scala-3/cats/derived/semigroupk.scala b/core/src/main/scala-3/cats/derived/semigroupk.scala
deleted file mode 100644
index c9b000f3..00000000
--- a/core/src/main/scala-3/cats/derived/semigroupk.scala
+++ /dev/null
@@ -1,14 +0,0 @@
-package cats.derived
-
-import cats.{Semigroup, SemigroupK}
-import shapeless3.deriving.{Const, K1}
-
-trait ProductSemigroupK[T[x[_]] <: SemigroupK[x], F[_]](using inst: K1.ProductInstances[T, F]) extends SemigroupK[F]:
-  def combineK[A](x: F[A], y: F[A]): F[A] = inst.map2[A, A, A](x, y)(
-    [t[_]] => (smgrpk: T[t], t0: t[A], t1: t[A]) => smgrpk.combineK(t0, t1)
-  )
-
-trait SemigroupKDerivation:
-  extension (F: SemigroupK.type)
-    inline def derived[F[_]](using gen: K1.ProductGeneric[F]): SemigroupK[F] =
-      new ProductSemigroupK[SemigroupK, F] {}
diff --git a/core/src/test/scala-3/cats/derived/MonoidKTests.scala b/core/src/test/scala-3/cats/derived/MonoidKTests.scala
index 80028a5d..e85a531e 100644
--- a/core/src/test/scala-3/cats/derived/MonoidKTests.scala
+++ b/core/src/test/scala-3/cats/derived/MonoidKTests.scala
@@ -2,7 +2,7 @@ package cats.derived
 
 import alleycats.*
 import cats.*
-import cats.derived.semiauto.*
+import cats.derived.*
 
 class MonoidKTests { //
   case class Foo[A](i: String, l: List[A]) derives MonoidK
diff --git a/core/src/test/scala-3/cats/derived/SemigroupKTests.scala b/core/src/test/scala-3/cats/derived/SemigroupKTests.scala
index e5030765..aa6b30d5 100644
--- a/core/src/test/scala-3/cats/derived/SemigroupKTests.scala
+++ b/core/src/test/scala-3/cats/derived/SemigroupKTests.scala
@@ -2,8 +2,7 @@ package cats.derived
 
 import alleycats.*
 import cats.*
-import cats.derived.semiauto.*
-import cats.derived.semiauto.given
+import cats.derived.*
 
 class SemigroupKTests { //
   case class Foo[A](i: String, l: List[A]) derives SemigroupK

From 415df3c052c160b3a12f29d25e00a3843f6e94ae Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Fri, 20 May 2022 17:19:31 +0100
Subject: [PATCH 2/8] WIP port of SemigroupK suite to scala 3

---
 .../cats/derived/DerivedSemigroupK.scala      |  4 ++
 .../cats/derived/SemigroupKSuite.scala        | 60 +++++++++++++++++++
 .../cats/derived/SemigroupKTests.scala        |  9 ---
 3 files changed, 64 insertions(+), 9 deletions(-)
 create mode 100644 core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
 delete mode 100644 core/src/test/scala-3/cats/derived/SemigroupKTests.scala

diff --git a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
index c6b92342..5a6826db 100644
--- a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
@@ -15,6 +15,10 @@ object DerivedSemigroupK:
   given [T](using T: Semigroup[T]): DerivedSemigroupK[Const[T]] = new SemigroupK[Const[T]]:
     final override def combineK[A](x: Const[T][A], y: Const[T][A]) = T.combine(x, y)
 
+  given [F[_], G[_]](using F: Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
+    given SemigroupK[G] = G.unify
+    F.unify.compose[G]
+
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedSemigroupK[F] =
     given K1.ProductInstances[SemigroupK, F] = inst.unify
     new Product[SemigroupK, F] {}
diff --git a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
new file mode 100644
index 00000000..bcbf2ec5
--- /dev/null
+++ b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
@@ -0,0 +1,60 @@
+package cats.derived
+
+import cats.*
+import cats.laws.discipline.{SemigroupKTests, SerializableTests}
+import org.scalacheck.Arbitrary
+
+class SemigroupKSuite extends KittensSuite {
+  import SemigroupKSuite.*
+  import TestDefns.*
+
+  def testSemigroupK(context: String)(implicit
+      // complexProduct: SemigroupK[ComplexProduct],
+      caseClassWOption: SemigroupK[CaseClassWOption],
+      boxMul: SemigroupK[BoxMul]
+  ): Unit = {
+    // checkAll(s"$context.SemigroupK[ComplexProduct]", SemigroupKTests[ComplexProduct].semigroupK[Char])
+    checkAll(s"$context.SemigroupK[CaseClassWOption]", SemigroupKTests[CaseClassWOption].semigroupK[Char])
+    checkAll(s"$context.SemigroupK[BoxMul]", SemigroupKTests[BoxMul].semigroupK[Char])
+    // checkAll(s"$context.SemigroupK is Serializable", SerializableTests.serializable(SemigroupK[ComplexProduct]))
+
+    test(s"$context.SemigroupK respects existing instances") {
+      assert(boxMul.combineK(Box(Mul[Char](5)), Box(Mul[Char](5))) == Box(Mul[Char](25)))
+    }
+  }
+
+  // locally {
+  //   import auto.semigroupK.given
+  //   testSemigroupK("auto")
+  // }
+
+  locally {
+    import semiInstances.given
+    testSemigroupK("semiauto")
+  }
+}
+
+object SemigroupKSuite {
+  import TestDefns._
+
+  type BoxMul[A] = Box[Mul[A]]
+
+  object semiInstances {
+    // implicit val complexProduct: SemigroupK[ComplexProduct] = semiauto.semigroupK
+    implicit val caseClassWOption: SemigroupK[CaseClassWOption] = semiauto.semigroupK
+    implicit val boxMul: SemigroupK[BoxMul] = semiauto.semigroupK
+  }
+
+  final case class Mul[T](value: Int)
+  object Mul {
+
+    implicit def eqv[T]: Eq[Mul[T]] = Eq.by(_.value)
+
+    implicit def arbitrary[T]: Arbitrary[Mul[T]] =
+      Arbitrary(Arbitrary.arbitrary[Int].map(apply))
+
+    implicit val semigroupK: SemigroupK[Mul] = new SemigroupK[Mul] {
+      def combineK[A](x: Mul[A], y: Mul[A]) = Mul(x.value * y.value)
+    }
+  }
+}
diff --git a/core/src/test/scala-3/cats/derived/SemigroupKTests.scala b/core/src/test/scala-3/cats/derived/SemigroupKTests.scala
deleted file mode 100644
index aa6b30d5..00000000
--- a/core/src/test/scala-3/cats/derived/SemigroupKTests.scala
+++ /dev/null
@@ -1,9 +0,0 @@
-package cats.derived
-
-import alleycats.*
-import cats.*
-import cats.derived.*
-
-class SemigroupKTests { //
-  case class Foo[A](i: String, l: List[A]) derives SemigroupK
-}

From 7f74610757953db6a9d876b357ebac1d53779dcb Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Fri, 20 May 2022 18:07:46 +0100
Subject: [PATCH 3/8] Nested derivations for SemigroupK

---
 .../cats/derived/DerivedSemigroupK.scala        |  7 +++++--
 .../src/main/scala-3/cats/derived/package.scala |  6 ++++++
 .../scala-3/cats/derived/SemigroupKSuite.scala  | 17 +++++++++--------
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
index 5a6826db..aa2638b9 100644
--- a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
@@ -15,10 +15,13 @@ object DerivedSemigroupK:
   given [T](using T: Semigroup[T]): DerivedSemigroupK[Const[T]] = new SemigroupK[Const[T]]:
     final override def combineK[A](x: Const[T][A], y: Const[T][A]) = T.combine(x, y)
 
-  given [F[_], G[_]](using F: Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
-    given SemigroupK[G] = G.unify
+  given [F[_], G[_]](using F: Or[F]): DerivedSemigroupK[[x] =>> F[G[x]]] =
     F.unify.compose[G]
 
+  given [F[_], G[_]](using F: DerivedApply.Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
+    new SemigroupK[[x] =>> F[G[x]]]:
+      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.unify.map2(x, y)(G.unify.combineK(_, _))
+
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedSemigroupK[F] =
     given K1.ProductInstances[SemigroupK, F] = inst.unify
     new Product[SemigroupK, F] {}
diff --git a/core/src/main/scala-3/cats/derived/package.scala b/core/src/main/scala-3/cats/derived/package.scala
index debf0a67..2fa7c556 100644
--- a/core/src/main/scala-3/cats/derived/package.scala
+++ b/core/src/main/scala-3/cats/derived/package.scala
@@ -104,3 +104,9 @@ object auto:
 
   object nonEmptyTraverse:
     inline given [F[_]](using NotGiven[NonEmptyTraverse[F]]): NonEmptyTraverse[F] = DerivedNonEmptyTraverse[F]
+
+  object semigroupK:
+    inline given [F[_]](using NotGiven[SemigroupK[F]]): SemigroupK[F] = DerivedSemigroupK[F]
+
+  object monoidK:
+    inline given [F[_]](using NotGiven[MonoidK[F]]): MonoidK[F] = DerivedMonoidK[F]
diff --git a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
index bcbf2ec5..7b79c9b3 100644
--- a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
+++ b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
@@ -9,24 +9,25 @@ class SemigroupKSuite extends KittensSuite {
   import TestDefns.*
 
   def testSemigroupK(context: String)(implicit
-      // complexProduct: SemigroupK[ComplexProduct],
+      complexProduct: SemigroupK[ComplexProduct],
       caseClassWOption: SemigroupK[CaseClassWOption],
       boxMul: SemigroupK[BoxMul]
   ): Unit = {
-    // checkAll(s"$context.SemigroupK[ComplexProduct]", SemigroupKTests[ComplexProduct].semigroupK[Char])
+    checkAll(s"$context.SemigroupK[ComplexProduct]", SemigroupKTests[ComplexProduct].semigroupK[Char])
     checkAll(s"$context.SemigroupK[CaseClassWOption]", SemigroupKTests[CaseClassWOption].semigroupK[Char])
     checkAll(s"$context.SemigroupK[BoxMul]", SemigroupKTests[BoxMul].semigroupK[Char])
-    // checkAll(s"$context.SemigroupK is Serializable", SerializableTests.serializable(SemigroupK[ComplexProduct]))
+    checkAll(s"$context.SemigroupK is Serializable", SerializableTests.serializable(SemigroupK[ComplexProduct]))
 
     test(s"$context.SemigroupK respects existing instances") {
       assert(boxMul.combineK(Box(Mul[Char](5)), Box(Mul[Char](5))) == Box(Mul[Char](25)))
     }
   }
 
-  // locally {
-  //   import auto.semigroupK.given
-  //   testSemigroupK("auto")
-  // }
+  locally {
+    import auto.semigroupK.given
+    summon[SemigroupK[[a] =>> Eval[Option[a]]]]
+    testSemigroupK("auto")
+  }
 
   locally {
     import semiInstances.given
@@ -40,7 +41,7 @@ object SemigroupKSuite {
   type BoxMul[A] = Box[Mul[A]]
 
   object semiInstances {
-    // implicit val complexProduct: SemigroupK[ComplexProduct] = semiauto.semigroupK
+    implicit val complexProduct: SemigroupK[ComplexProduct] = semiauto.semigroupK
     implicit val caseClassWOption: SemigroupK[CaseClassWOption] = semiauto.semigroupK
     implicit val boxMul: SemigroupK[BoxMul] = semiauto.semigroupK
   }

From fe2b8b44226f4f49212c0bdc2bba26765389fcd5 Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Mon, 23 May 2022 11:44:06 +0100
Subject: [PATCH 4/8] Priority for derived SemigroupK given instances

---
 .../scala-3/cats/derived/DerivedSemigroupK.scala    | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
index aa2638b9..26b6f124 100644
--- a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
@@ -6,7 +6,7 @@ import shapeless3.deriving.{Const, K1}
 import scala.compiletime.*
 
 type DerivedSemigroupK[F[_]] = Derived[SemigroupK[F]]
-object DerivedSemigroupK:
+object DerivedSemigroupK extends DerivedSemigroupKInstances1:
   type Or[F[_]] = Derived.Or[SemigroupK[F]]
   inline def apply[F[_]]: SemigroupK[F] =
     import DerivedSemigroupK.given
@@ -18,10 +18,6 @@ object DerivedSemigroupK:
   given [F[_], G[_]](using F: Or[F]): DerivedSemigroupK[[x] =>> F[G[x]]] =
     F.unify.compose[G]
 
-  given [F[_], G[_]](using F: DerivedApply.Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
-    new SemigroupK[[x] =>> F[G[x]]]:
-      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.unify.map2(x, y)(G.unify.combineK(_, _))
-
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedSemigroupK[F] =
     given K1.ProductInstances[SemigroupK, F] = inst.unify
     new Product[SemigroupK, F] {}
@@ -29,3 +25,10 @@ object DerivedSemigroupK:
   trait Product[T[x[_]] <: SemigroupK[x], F[_]](using inst: K1.ProductInstances[T, F]) extends SemigroupK[F]:
     final override def combineK[A](x: F[A], y: F[A]): F[A] =
       inst.map2[A, A, A](x, y)([t[_]] => (smgrpk: T[t], x: t[A], y: t[A]) => smgrpk.combineK(x, y))
+
+trait DerivedSemigroupKInstances1:
+  import DerivedSemigroupK.Or
+
+  given [F[_], G[_]](using F: DerivedApply.Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
+    new SemigroupK[[x] =>> F[G[x]]]:
+      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.unify.map2(x, y)(G.unify.combineK(_, _))

From 84b06644398f17e1184134fcbc172b208c8bb2a7 Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Mon, 23 May 2022 12:01:50 +0100
Subject: [PATCH 5/8] Port scala 2 MonoidK tests to scala 3

---
 .../scala-3/cats/derived/DerivedMonoidK.scala | 19 +++++-
 .../scala-3/cats/derived/MonoidKSuite.scala   | 64 +++++++++++++++++++
 .../scala-3/cats/derived/MonoidKTests.scala   |  9 ---
 3 files changed, 81 insertions(+), 11 deletions(-)
 create mode 100644 core/src/test/scala-3/cats/derived/MonoidKSuite.scala
 delete mode 100644 core/src/test/scala-3/cats/derived/MonoidKTests.scala

diff --git a/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
index 9b8925f6..d1ca05c2 100644
--- a/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
@@ -1,12 +1,12 @@
 package cats.derived
 
-import cats.{Monoid, MonoidK}
+import cats.*
 import shapeless3.deriving.{Const, K1}
 
 import scala.compiletime.*
 
 type DerivedMonoidK[F[_]] = Derived[MonoidK[F]]
-object DerivedMonoidK:
+object DerivedMonoidK extends DerivedMonoidKInstances1:
   type Or[F[_]] = Derived.Or[MonoidK[F]]
   inline def apply[F[_]]: MonoidK[F] =
     import DerivedMonoidK.given
@@ -17,6 +17,9 @@ object DerivedMonoidK:
 
     final override def combineK[A](x: Const[T][A], y: Const[T][A]) = T.combine(x, y)
 
+  given [F[_], G[_]](using F: Or[F]): DerivedMonoidK[[x] =>> F[G[x]]] =
+    F.unify.compose[G]
+
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedMonoidK[F] =
     given K1.ProductInstances[MonoidK, F] = inst.unify
     new Product[MonoidK, F] {}
@@ -25,3 +28,15 @@ object DerivedMonoidK:
       extends MonoidK[F],
         DerivedSemigroupK.Product[T, F]:
     final override def empty[A]: F[A] = inst.construct([t[_]] => (emp: T[t]) => emp.empty[A])
+
+trait DerivedMonoidKInstances1:
+  import DerivedMonoidK.Or
+
+  given [F[_], G[_]](using F0: DerivedApplicative.Or[F], G0: Or[G]): DerivedMonoidK[[x] =>> F[G[x]]] =
+    new MonoidK[[x] =>> F[G[x]]]:
+      val F: Applicative[F] = F0.unify
+      val G: MonoidK[G] = G0.unify
+
+      final override def empty[A]: F[G[A]] = F.pure(G.empty[A])
+
+      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.map2(x, y)(G.combineK(_, _))
diff --git a/core/src/test/scala-3/cats/derived/MonoidKSuite.scala b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
new file mode 100644
index 00000000..b5fa1b18
--- /dev/null
+++ b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
@@ -0,0 +1,64 @@
+package cats.derived
+
+import alleycats.*
+import cats.*
+import cats.derived.*
+import cats.laws.discipline.{MonoidKTests, SerializableTests}
+import org.scalacheck.Arbitrary
+
+class MonoidKSuite extends KittensSuite {
+  import MonoidKSuite.*
+  import TestDefns.*
+
+  def testMonoidK(context: String)(implicit
+      complexProduct: MonoidK[ComplexProduct],
+      caseClassWOption: MonoidK[CaseClassWOption],
+      boxMul: MonoidK[BoxMul]
+  ): Unit = {
+    checkAll(s"$context.MonoidK[ComplexProduct]", MonoidKTests[ComplexProduct].monoidK[Char])
+    checkAll(s"$context.MonoidK[CaseClassWOption]", MonoidKTests[CaseClassWOption].monoidK[Char])
+    checkAll(s"$context.MonoidK[BoxMul]", MonoidKTests[BoxMul].monoidK[Char])
+    checkAll(s"$context.MonoidK is Serializable", SerializableTests.serializable(MonoidK[ComplexProduct]))
+
+    test(s"$context.MonoidK respects existing instances") {
+      assert(boxMul.empty[Char] == Box(Mul[Char](1)))
+      assert(boxMul.combineK(Box(Mul[Char](5)), Box(Mul[Char](5))) == Box(Mul[Char](25)))
+    }
+  }
+
+  {
+    import auto.monoidK.given
+    testMonoidK("auto")
+  }
+
+  {
+    import semiInstances.given
+    testMonoidK("semi")
+  }
+}
+
+object MonoidKSuite {
+  import TestDefns._
+
+  type BoxMul[A] = Box[Mul[A]]
+
+  object semiInstances {
+    implicit val complexProduct: MonoidK[ComplexProduct] = semiauto.monoidK
+    implicit val caseClassWOption: MonoidK[CaseClassWOption] = semiauto.monoidK
+    implicit val boxMul: MonoidK[BoxMul] = semiauto.monoidK
+  }
+
+  final case class Mul[T](value: Int)
+  object Mul {
+
+    implicit def eqv[T]: Eq[Mul[T]] = Eq.by(_.value)
+
+    implicit def arbitrary[T]: Arbitrary[Mul[T]] =
+      Arbitrary(Arbitrary.arbitrary[Int].map(apply))
+
+    implicit val monoidK: MonoidK[Mul] = new MonoidK[Mul] {
+      def empty[A] = Mul(1)
+      def combineK[A](x: Mul[A], y: Mul[A]) = Mul(x.value * y.value)
+    }
+  }
+}
diff --git a/core/src/test/scala-3/cats/derived/MonoidKTests.scala b/core/src/test/scala-3/cats/derived/MonoidKTests.scala
deleted file mode 100644
index e85a531e..00000000
--- a/core/src/test/scala-3/cats/derived/MonoidKTests.scala
+++ /dev/null
@@ -1,9 +0,0 @@
-package cats.derived
-
-import alleycats.*
-import cats.*
-import cats.derived.*
-
-class MonoidKTests { //
-  case class Foo[A](i: String, l: List[A]) derives MonoidK
-}

From a1e9750fcb7bb331f3f98f28d55a542680327162 Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Mon, 23 May 2022 17:56:32 +0100
Subject: [PATCH 6/8] Various improvements

- ImplicitNotFound error for SemigroupK/MonoidK
- Replace given priority via traits with NotGiven
---
 .../scala-3/cats/derived/DerivedMonoidK.scala | 38 ++++++++++++-------
 .../cats/derived/DerivedSemigroupK.scala      | 24 +++++++-----
 .../scala-3/cats/derived/MonoidKSuite.scala   |  4 +-
 .../cats/derived/SemigroupKSuite.scala        |  1 -
 4 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
index d1ca05c2..3f9d64be 100644
--- a/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
@@ -3,10 +3,19 @@ package cats.derived
 import cats.*
 import shapeless3.deriving.{Const, K1}
 
+import scala.annotation.implicitNotFound
 import scala.compiletime.*
-
+import scala.util.NotGiven
+
+@implicitNotFound("""Could not derive an instance of MonoidK[F] where F = ${F}.
+Make sure that F[_] satisfies one of the following conditions:
+  * it is a constant type [x] =>> T where T: Monoid
+  * it is a nested type [x] =>> G[H[x]] where G: MonoidK
+  * it is a nested type [x] =>> G[H[x]] where G: Applicative and H: MonoidK
+  * it is a generic case class where all fields have a MonoidK instance
+""")
 type DerivedMonoidK[F[_]] = Derived[MonoidK[F]]
-object DerivedMonoidK extends DerivedMonoidKInstances1:
+object DerivedMonoidK:
   type Or[F[_]] = Derived.Or[MonoidK[F]]
   inline def apply[F[_]]: MonoidK[F] =
     import DerivedMonoidK.given
@@ -20,6 +29,19 @@ object DerivedMonoidK extends DerivedMonoidKInstances1:
   given [F[_], G[_]](using F: Or[F]): DerivedMonoidK[[x] =>> F[G[x]]] =
     F.unify.compose[G]
 
+  given [F[_], G[_]](using
+      N: NotGiven[Or[F]],
+      F0: DerivedApplicative.Or[F],
+      G0: Or[G]
+  ): DerivedMonoidK[[x] =>> F[G[x]]] =
+    new MonoidK[[x] =>> F[G[x]]]:
+      val F: Applicative[F] = F0.unify
+      val G: MonoidK[G] = G0.unify
+
+      final override def empty[A]: F[G[A]] = F.pure(G.empty[A])
+
+      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.map2(x, y)(G.combineK(_, _))
+
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedMonoidK[F] =
     given K1.ProductInstances[MonoidK, F] = inst.unify
     new Product[MonoidK, F] {}
@@ -28,15 +50,3 @@ object DerivedMonoidK extends DerivedMonoidKInstances1:
       extends MonoidK[F],
         DerivedSemigroupK.Product[T, F]:
     final override def empty[A]: F[A] = inst.construct([t[_]] => (emp: T[t]) => emp.empty[A])
-
-trait DerivedMonoidKInstances1:
-  import DerivedMonoidK.Or
-
-  given [F[_], G[_]](using F0: DerivedApplicative.Or[F], G0: Or[G]): DerivedMonoidK[[x] =>> F[G[x]]] =
-    new MonoidK[[x] =>> F[G[x]]]:
-      val F: Applicative[F] = F0.unify
-      val G: MonoidK[G] = G0.unify
-
-      final override def empty[A]: F[G[A]] = F.pure(G.empty[A])
-
-      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.map2(x, y)(G.combineK(_, _))
diff --git a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
index 26b6f124..b826cf28 100644
--- a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
@@ -3,10 +3,19 @@ package cats.derived
 import cats.{Semigroup, SemigroupK}
 import shapeless3.deriving.{Const, K1}
 
+import scala.annotation.implicitNotFound
 import scala.compiletime.*
-
+import scala.util.NotGiven
+
+@implicitNotFound("""Could not derive an instance of SemigroupK[F] where F = ${F}.
+Make sure that F[_] satisfies one of the following conditions:
+  * it is a constant type [x] =>> T where T: Semigroup
+  * it is a nested type [x] =>> G[H[x]] where G: SemigroupK
+  * it is a nested type [x] =>> G[H[x]] where G: Apply and H: SemigroupK
+  * it is a generic case class where all fields have a SemigroupK instance
+""")
 type DerivedSemigroupK[F[_]] = Derived[SemigroupK[F]]
-object DerivedSemigroupK extends DerivedSemigroupKInstances1:
+object DerivedSemigroupK:
   type Or[F[_]] = Derived.Or[SemigroupK[F]]
   inline def apply[F[_]]: SemigroupK[F] =
     import DerivedSemigroupK.given
@@ -18,6 +27,10 @@ object DerivedSemigroupK extends DerivedSemigroupKInstances1:
   given [F[_], G[_]](using F: Or[F]): DerivedSemigroupK[[x] =>> F[G[x]]] =
     F.unify.compose[G]
 
+  given [F[_], G[_]](using N: NotGiven[Or[F]], F: DerivedApply.Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
+    new SemigroupK[[x] =>> F[G[x]]]:
+      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.unify.map2(x, y)(G.unify.combineK(_, _))
+
   given [F[_]](using inst: => K1.ProductInstances[Or, F]): DerivedSemigroupK[F] =
     given K1.ProductInstances[SemigroupK, F] = inst.unify
     new Product[SemigroupK, F] {}
@@ -25,10 +38,3 @@ object DerivedSemigroupK extends DerivedSemigroupKInstances1:
   trait Product[T[x[_]] <: SemigroupK[x], F[_]](using inst: K1.ProductInstances[T, F]) extends SemigroupK[F]:
     final override def combineK[A](x: F[A], y: F[A]): F[A] =
       inst.map2[A, A, A](x, y)([t[_]] => (smgrpk: T[t], x: t[A], y: t[A]) => smgrpk.combineK(x, y))
-
-trait DerivedSemigroupKInstances1:
-  import DerivedSemigroupK.Or
-
-  given [F[_], G[_]](using F: DerivedApply.Or[F], G: Or[G]): DerivedSemigroupK[[x] =>> F[G[x]]] =
-    new SemigroupK[[x] =>> F[G[x]]]:
-      final override def combineK[A](x: F[G[A]], y: F[G[A]]): F[G[A]] = F.unify.map2(x, y)(G.unify.combineK(_, _))
diff --git a/core/src/test/scala-3/cats/derived/MonoidKSuite.scala b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
index b5fa1b18..f36190c5 100644
--- a/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
+++ b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
@@ -32,7 +32,7 @@ class MonoidKSuite extends KittensSuite {
   }
 
   {
-    import semiInstances.given
+    import monInstances.given
     testMonoidK("semi")
   }
 }
@@ -42,7 +42,7 @@ object MonoidKSuite {
 
   type BoxMul[A] = Box[Mul[A]]
 
-  object semiInstances {
+  object monInstances {
     implicit val complexProduct: MonoidK[ComplexProduct] = semiauto.monoidK
     implicit val caseClassWOption: MonoidK[CaseClassWOption] = semiauto.monoidK
     implicit val boxMul: MonoidK[BoxMul] = semiauto.monoidK
diff --git a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
index 7b79c9b3..b914fa70 100644
--- a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
+++ b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
@@ -25,7 +25,6 @@ class SemigroupKSuite extends KittensSuite {
 
   locally {
     import auto.semigroupK.given
-    summon[SemigroupK[[a] =>> Eval[Option[a]]]]
     testSemigroupK("auto")
   }
 

From 819ab4f8bdc3ecde470ef63002472c3dce0d171f Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Tue, 24 May 2022 11:00:26 +0100
Subject: [PATCH 7/8] Use inline in tests

---
 .../scala-3/cats/derived/DerivedMonoidK.scala |  3 +--
 .../cats/derived/DerivedSemigroupK.scala      |  3 +--
 .../scala-3/cats/derived/MonoidKSuite.scala   | 22 +++++++++----------
 .../cats/derived/SemigroupKSuite.scala        | 22 ++++++++++---------
 4 files changed, 25 insertions(+), 25 deletions(-)

diff --git a/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
index 3f9d64be..69cc75d0 100644
--- a/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedMonoidK.scala
@@ -12,8 +12,7 @@ Make sure that F[_] satisfies one of the following conditions:
   * it is a constant type [x] =>> T where T: Monoid
   * it is a nested type [x] =>> G[H[x]] where G: MonoidK
   * it is a nested type [x] =>> G[H[x]] where G: Applicative and H: MonoidK
-  * it is a generic case class where all fields have a MonoidK instance
-""")
+  * it is a generic case class where all fields have a MonoidK instance""")
 type DerivedMonoidK[F[_]] = Derived[MonoidK[F]]
 object DerivedMonoidK:
   type Or[F[_]] = Derived.Or[MonoidK[F]]
diff --git a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
index b826cf28..d3099cfb 100644
--- a/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
+++ b/core/src/main/scala-3/cats/derived/DerivedSemigroupK.scala
@@ -12,8 +12,7 @@ Make sure that F[_] satisfies one of the following conditions:
   * it is a constant type [x] =>> T where T: Semigroup
   * it is a nested type [x] =>> G[H[x]] where G: SemigroupK
   * it is a nested type [x] =>> G[H[x]] where G: Apply and H: SemigroupK
-  * it is a generic case class where all fields have a SemigroupK instance
-""")
+  * it is a generic case class where all fields have a SemigroupK instance""")
 type DerivedSemigroupK[F[_]] = Derived[SemigroupK[F]]
 object DerivedSemigroupK:
   type Or[F[_]] = Derived.Or[SemigroupK[F]]
diff --git a/core/src/test/scala-3/cats/derived/MonoidKSuite.scala b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
index f36190c5..eedc7e28 100644
--- a/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
+++ b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
@@ -5,24 +5,24 @@ import cats.*
 import cats.derived.*
 import cats.laws.discipline.{MonoidKTests, SerializableTests}
 import org.scalacheck.Arbitrary
+import scala.compiletime.*
 
 class MonoidKSuite extends KittensSuite {
   import MonoidKSuite.*
   import TestDefns.*
 
-  def testMonoidK(context: String)(implicit
-      complexProduct: MonoidK[ComplexProduct],
-      caseClassWOption: MonoidK[CaseClassWOption],
-      boxMul: MonoidK[BoxMul]
-  ): Unit = {
-    checkAll(s"$context.MonoidK[ComplexProduct]", MonoidKTests[ComplexProduct].monoidK[Char])
-    checkAll(s"$context.MonoidK[CaseClassWOption]", MonoidKTests[CaseClassWOption].monoidK[Char])
-    checkAll(s"$context.MonoidK[BoxMul]", MonoidKTests[BoxMul].monoidK[Char])
-    checkAll(s"$context.MonoidK is Serializable", SerializableTests.serializable(MonoidK[ComplexProduct]))
+  inline def monoidKTests[F[_]]: MonoidKTests[F] = MonoidKTests[F](summonInline)
+
+  inline def testMonoidK(context: String): Unit = {
+    checkAll(s"$context.MonoidK[ComplexProduct]", monoidKTests[ComplexProduct].monoidK[Char])
+    checkAll(s"$context.MonoidK[CaseClassWOption]", monoidKTests[CaseClassWOption].monoidK[Char])
+    checkAll(s"$context.MonoidK[BoxMul]", monoidKTests[BoxMul].monoidK[Char])
+    checkAll(s"$context.MonoidK is Serializable", SerializableTests.serializable(summonInline[MonoidK[ComplexProduct]]))
 
     test(s"$context.MonoidK respects existing instances") {
-      assert(boxMul.empty[Char] == Box(Mul[Char](1)))
-      assert(boxMul.combineK(Box(Mul[Char](5)), Box(Mul[Char](5))) == Box(Mul[Char](25)))
+      val M = summonInline[MonoidK[BoxMul]]
+      assert(M.empty[Char] == Box(Mul[Char](1)))
+      assert(M.combineK(Box(Mul[Char](5)), Box(Mul[Char](5))) == Box(Mul[Char](25)))
     }
   }
 
diff --git a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
index b914fa70..b7eaa75b 100644
--- a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
+++ b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
@@ -3,23 +3,25 @@ package cats.derived
 import cats.*
 import cats.laws.discipline.{SemigroupKTests, SerializableTests}
 import org.scalacheck.Arbitrary
+import scala.compiletime.*
 
 class SemigroupKSuite extends KittensSuite {
   import SemigroupKSuite.*
   import TestDefns.*
 
-  def testSemigroupK(context: String)(implicit
-      complexProduct: SemigroupK[ComplexProduct],
-      caseClassWOption: SemigroupK[CaseClassWOption],
-      boxMul: SemigroupK[BoxMul]
-  ): Unit = {
-    checkAll(s"$context.SemigroupK[ComplexProduct]", SemigroupKTests[ComplexProduct].semigroupK[Char])
-    checkAll(s"$context.SemigroupK[CaseClassWOption]", SemigroupKTests[CaseClassWOption].semigroupK[Char])
-    checkAll(s"$context.SemigroupK[BoxMul]", SemigroupKTests[BoxMul].semigroupK[Char])
-    checkAll(s"$context.SemigroupK is Serializable", SerializableTests.serializable(SemigroupK[ComplexProduct]))
+  inline def semigroupKTests[F[_]]: SemigroupKTests[F] = SemigroupKTests[F](summonInline)
+
+  inline def testSemigroupK(context: String): Unit = {
+    checkAll(s"$context.SemigroupK[ComplexProduct]", semigroupKTests[ComplexProduct].semigroupK[Char])
+    checkAll(s"$context.SemigroupK[CaseClassWOption]", semigroupKTests[CaseClassWOption].semigroupK[Char])
+    checkAll(s"$context.SemigroupK[BoxMul]", semigroupKTests[BoxMul].semigroupK[Char])
+    checkAll(
+      s"$context.SemigroupK is Serializable",
+      SerializableTests.serializable(summonInline[SemigroupK[ComplexProduct]])
+    )
 
     test(s"$context.SemigroupK respects existing instances") {
-      assert(boxMul.combineK(Box(Mul[Char](5)), Box(Mul[Char](5))) == Box(Mul[Char](25)))
+      assert(summonInline[SemigroupK[BoxMul]].combineK(Box(Mul[Char](5)), Box(Mul[Char](5))) == Box(Mul[Char](25)))
     }
   }
 

From fc2fced5ac1cc0d66a009132e6bdef0f580822f4 Mon Sep 17 00:00:00 2001
From: Tim Spence <timothywspence@gmail.com>
Date: Tue, 24 May 2022 11:15:46 +0100
Subject: [PATCH 8/8] SemigroupK/MonoidK test for derives syntax

---
 core/src/test/scala-3/cats/derived/MonoidKSuite.scala    | 3 +++
 core/src/test/scala-3/cats/derived/SemigroupKSuite.scala | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/core/src/test/scala-3/cats/derived/MonoidKSuite.scala b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
index eedc7e28..9a0ad5ad 100644
--- a/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
+++ b/core/src/test/scala-3/cats/derived/MonoidKSuite.scala
@@ -61,4 +61,7 @@ object MonoidKSuite {
       def combineK[A](x: Mul[A], y: Mul[A]) = Mul(x.value * y.value)
     }
   }
+
+  case class Simple[A](value1: List[A], value2: Set[A]) derives MonoidK
+  case class Recursive[A](first: List[A], rest: Recursive[A]) derives MonoidK
 }
diff --git a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
index b7eaa75b..6214ac03 100644
--- a/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
+++ b/core/src/test/scala-3/cats/derived/SemigroupKSuite.scala
@@ -59,4 +59,7 @@ object SemigroupKSuite {
       def combineK[A](x: Mul[A], y: Mul[A]) = Mul(x.value * y.value)
     }
   }
+
+  case class Simple[A](value1: List[A], value2: Set[A]) derives SemigroupK
+  case class Recursive[A](first: List[A], rest: Recursive[A]) derives SemigroupK
 }